THE BRYOZOA BASSLER. 343 



nomenclature that it failed to gain acceptance. The labors of 

 Nitsche, Allman, and Busk have fixed the principal groups. To 

 Nitsche 2 is due the division into the two groups Ectoprocta and 

 Entoprocta, the latter containing only a few, singular genera such 

 as Pedicellina and Loxosoma. Allman 3 formed the orders Phylac- 

 tolaemata and Gymnolaemata, the latter including most of the 

 bryozoa and all forms capable of preservation as fossils. Busk's 

 suborders Cheilostomata, Cyclostomata, and Ctenostomata 4 are now 

 generally accepted as orders. To these Ulrich, in 1882, 5 added the 

 Trepostomata, to include, besides uncontested bryozoa, a number of 

 forms which had been generally regarded as corals; and Vine, in 

 1883, 6 added the Cryptostomata, which like the Trepostomata is 

 known only from fossil forms. 



The brj^ozoa and the brachiopoda are considered as constituting 

 the phylum Molluscoidea, although some authors believe there is no 

 relationship between them and regard the bryozoa as representing a 

 distinct phylum. The two large subdivisions of the bryozoa, Ecto- 

 procta and Entoprocta, based upon the position of the anus with 

 reference to the tentacles, have been mentioned before. These sub- 

 classes differ widely from each other in many respects and here again 

 some authors believe they are not even distantly related. However, 

 the great majority of these animals belong to the Ectoprocta and 

 under this to the superorder Gymnolaemata. Five orders of Gym- 

 nolaemata are known, of which the Cheilostomata is perhaps the 

 largest in number of species. The relations of these various classi- 

 ficatory terms are expressed in the following table : 



Phylum MOLLUSCOIDEA. 



Class BRYOZOA. 

 Subclass ENTOPROCTA. 



Row of tentacles circular, inclosing both the mouth and anal orifice. 

 Subclass ECTOPROCTA. 



The tentacles surround the mouth only. 



Superorder PHYLACTOLAEMATA. 



Fresh-water Ectoprocta with the tentacles arranged in horseshoe shape and 

 the mouth protected by an overhanging lip. 



Superorder GYMNOLAEMATA. 



Almost exclusively marine Ectoprocta with a circular row of tentacles sur- 

 rounding the mouth, which is at their center. 



2 1869. Nitsche. Beitschrift fiir wissenschaftliche Zoologie, Vol. XX. 



3 1856. Allman. Monograph of the Freshwater Polyzoa, p. 10. 



* 1852. Busk. British Museum. Catalogue of Marine Polyzoa. 



6 1882. Ulrich. Journal Cincinnati Society Natural History, Vol. V, p. 151. 



1883. Vine. Report British Association Advancement Science, p. 196. 



